The Han dynasty was founded by Liu Bang (best known by his temple name, Gaozu), who assumed the title of emperor in 202 bce. Eleven members of the Liu family followed in his place as effective emperors until 6 ce (a 12th briefly occupied the throne as a puppet). In 9 ce the dynastic line was challenged by Wang Mang, who established his own regime under the title of Xin. In 25 ce the authority of the Han dynasty was reaffirmed by Liu Xiu (posthumous name Guangwudi), who reigned as Han emperor until 57. Thirteen of his descendants maintained the dynastic succession until 220, when the rule of a single empire was replaced by that of three separate kingdoms. While the entire period from 206 (or 202) bce to 220 ce is generally described as that of the Han dynasty, the terms Xi (Western) Han (also called Former Han) and Dong (Eastern) Han (also called Later Han) are used to denote the two subperiods. During the first period, from 206 bce to 25 ce, the capital city was situated at Chang’an (modern Xi’an), in the west; in the second period, from 25 to 220 ce, it lay farther east at Luoyang.

The four centuries in question may be treated as a single historical period by virtue of dynastic continuity, for, apart from the short interval of 9–25, imperial authority was unquestionably vested in successive members of the same family. The period, however, was one of considerable changes in imperial, political, and social development. Organs of government were established, tried, modified, or replaced, and new social distinctions were brought into being. Chinese prestige among other peoples varied with the political stability and military strength of the Han house, and the extent of territory that was subject to the jurisdiction of Han officials varied with the success of Han arms. At the same time, the example of the palace, the activities of government, and the growing luxuries of city life gave rise to new standards of cultural and technological achievement.

China’s first imperial dynasty, that of Qin, had lasted barely 15 years before its dissolution in the face of rebellion and civil war. By contrast, Han formed the first long-lasting regime that could successfully claim to be the sole authority entitled to wield administrative power. The Han forms of government, however, were derived in the first instance from the Qin dynasty, and these in turn incorporated a number of features of the government that had been practiced by earlier kingdoms. The Han empire left as a heritage a practical example of imperial government and an ideal of dynastic authority to which its successors aspired. But the Han period has been credited with more success than is its due; it has been represented as a period of 400 years of effective dynastic rule, punctuated by a short period in which a pretender to power usurped authority, and it has been assumed that imperial unity and effective administration advanced steadily with each decade. In fact, there were only a few short periods marked by dynastic strength, stable government, and intensive administration. Several reigns were characterized by palace intrigue and corrupt influences at court, and on a number of occasions the future of the dynasty was seriously endangered by outbreaks of violence, seizure of political power, or a crisis in the imperial succession.

Dynastic authority and the succession of emperors

Since at least as early as the Shang dynasty, the Chinese had been accustomed to acknowledging the temporal and spiritual authority of a single leader and its transmission within a family, at first from brother to brother and later from father to son. Some of the early kings had been military commanders, and they may have organized the corporate work of the community, such as the manufacture of bronze tools and vessels. In addition, they acted as religious leaders, appointing scribes or priests to consult the oracles and thus to assist in making major decisions covering communal activities, such as warfare and hunting expeditions. In succeeding centuries the growing sophistication of Chinese culture was accompanied by demands for more-intensive political organization and for more-regular administration; as kings came to delegate tasks to more officials, so was their own authority enhanced and the obedience that they commanded the more widely acknowledged. Under the kingdoms of Zhou, an association was deliberately fostered between the authority of the king and the dispensation exercised over the universe by heaven, with the result that the kings of Zhou and, later, the emperors of Chinese dynasties were regarded as being the sons of heaven.